NGC371

After what has seemed like an eternity of rain and clouds, we finally had a clear night, and I was determined not to waste it. (There had been two almost-but-not-quite nights in the previous week. I had all the gear setup and ready to go, only for all the clouds to roll in and spoil the party.) By about 10pm the clouds had all vanished and even with the full moon I was able to get some good data.

Or so I thought…

I’m still coming to terms with the OSC and what settings I need for shooting in light-polluted suburban skies. I think I over-cooked the exposure time as there was a lot of blue to the subs. A lot of blue. I suspect I’m still trying to run the OSC as if it was a DSLR - and where I could (reasonably) safely get a way with 30 second (or even longer) subs with the DSLR, the OSC is a different beast.

I suspect I also need better flats, for the corners of the stacked image turned out to be very vignetted and I had to crop the image a lot to get something that looked good. (Although with such a wide FoV, I need to crop a lot anyway…)

This was also my first meridian flip, too. I was watching Ekos count down to ‘Launch!’ only have a ‘NASA moment’ and the initial flip failed for some unlogged reason. The second attempt 4 minutes later went off without a hitch and I happily watched the mount do a 180-degree flip.

However, the gremlins weren’t done with me… Ekos decided that it wasn’t going to carry on with the imaging sequence. The post-flip re-alignment seemed to go OK, only for the guiding to pack in. I suspect this was probably because the moonlight was now hitting the side of the guide scope and somehow bouncing back to the guide camera. At this point Ekos crashed, so I gave up and packed everything away. It was approaching midnight on a work-day, so probably a wise idea…

On the plus side, I did manage to get 154 subs out of the 240 I had hoped for. Not perfect, but given how over-exposed they all were, probably a good thing to have it fail.

How was the guiding, you ask? Prior to the meridian flip it was guiding consistently below 0.8 RMS, sometimes dipping down to 0.6 or lower. In other words, bloody well.

Image details:

  • Gain: 25
  • Offset: 10
  • Temperature: 0 degrees C
  • Exposure: 20 seconds
  • Lights: 154
  • Darks: 30
  • Flats: 38 (Recycled from another imaging session with the same optical train, although different gain+offset)
  • Bias: 44
  • Stacked and pre-proc’d in SiriL, finished in Affinity Photo

NGC371